As rolling lines for rolling metallic materials to make rolled materials, there are steel sheet manufacturing hot sheet rolling lines, plate rolling lines, and cold rolling lines, aluminum or copper rolling lines, etc. Among them, hot sheet rolling lines, plate rolling lines, and the like have a function of directly pouring water to a rolling material to control temperatures of the rolling material itself. All rolling lines have a function of cooling rolling rolls and the like working for a rolling material to be rolled thereon. Cooling water to be directly poured to a rolling material itself like the former case is called direct cooling water. Cooling water to be poured to rolling rolls and the like working for a rolling material to be rolled thereon is called indirect cooling water. They are collectively referred to as cooling water.
In particular, hot sheet rolling lines as well as plate rolling lines serving to roll a rolling material having as high temperatures as 1,000 degrees C. or near need a great deal of direct cooling water for the cooling. Further, there is needed a plenty of indirect cooling water for cooling rolling rolls contacting the high-temperature material.
For such reasons, there have been techniques proposed for cooling systems in rolling lines, including e.g. controlling valves in a cooling system to adjust cooling water flow rates or the like (refer to e.g. PTLs 1 to 3 below).